How to begins

How to build an inexpensive two speed emotor bike. The story begins with the search for a wheel.

Now I usually use a scooter rear wheel with the motor bracket attached. But for this build I am trying to go for the easy to find, anyone can do it, build instructions. So I have decided to use a wheel from a child's 16 inch bike. The thrift store had one for eight bucks but I wanted to see if I could find one for a better price.

I did order a chain sprocket for the scooter motor from tnc and one of their motor brackets that mounts on the wheel as well. I figure if I can't use it, I can probably get some ideas from it. So I'm on hold for a while.

Yesterday the how to project was just to look at the thrift store for a very cheap pusher wheel. I'm not sure what, if anything, will get done today. I am still getting the house ready to paint.

Yesterday I hung a new walk in door for my shop. I bought a $19 masonite door. It cost more for the hinges than the door. It's a good thing I got a cheap one because I had to custom fit it. The fitting isn't perfect. I may have to get another one and rehang it later.

But I hope to get something done on the pusher book as well. I think a good 16" bike wheel is the way to go. Working with the door for two days has given me an Idea. One of the things everyone using a pusher needs is the ability to fold it up for easy storage.

I had never thought of making a U shaped frame for the bike and another one for the pusher trailer then bolting them both to a hinge. It will allow the pusher to go up and down without any side wobble that has been a problem in the past. So that is the plan for this one. At least that is the first thing in the morning plan which usually changes.

You know since I am making a cheap easy to build one for the "How To", I guess the hinge is too ambitious. Oh well on the next one.

After dinner tonight we went by the thrift store so I could check out bikes. I can get a nice clean 16inch for about ten bucks there. I want to look at a church and yard sale or two tomorrow then pick up one somewhere. I also need to look for a motor. I have the sprocket and mount on the way so I will be doing some more planning this weekend.

I went to a couple of yard sales and found a bike today. I bought the one below to use as a donar for the rear wheel and chain. I probably will pull the crank and handlebars as well. I think the crank might be good if I ever build a bike with a strong enough drive that the pedals are just to get the bike moving from a dead stop.

I will update this entry from time to time until the build is finished. I am only counting things that actually got used in the build..... I have a motor sprocket to convert the motor to a bike chain but I am also looking at a rear sprocket to convert the wheel to #25 chain. I will only count the one I use into the build cost. You can drastically reduce the cost if you have anything laying around to substitute.

purchases so far

One yard sale donor bike $5
on off on switch $2
motor (a) $35 (ebay)
sprocket for pusher wheel $10
@25 chain and master link (a)$10
frame material and L brackets $20



Tools used so far

15mm wrench to remove rear wheel
14mm wrench to remove front wheel
17mm wrench to remove coaster brake lever.
chain tool... walmart pretty much good for one project if you are careful.
screwdrivers
Vise grips are always nice to have around

STEP ONE
strip donor bike

First you will probably need to remove the chain guard. Cheap plastic headed for the land fill. Mine was held on with a couple of Phillips screws.

Then you will need to loosen the bolts holding the rear wheel on. I found a couple of dropout locks as well. You might need to completely remove the bolts and any other hardware holding the rear wheel in place. Remove the brake lever clamp so that the wheel will move freely.

Move the wheel in the drop out slots until the chain is loose. Work the wheel out of the drop outs.

At this point it should look like this....

Next you should remove the brake lever... at that point you wheel will look like this..

Use your chain breaker to push out one of the rivets in the chain. I push mine ten half turns and then twist the chain. This should leave the rivet hanging so that you can use it to reuse that chain later.

At this point you can toss the rest of the bike if you want to. I however always junk it out as much as possible. For instance on twenty inch bikes and up the cranks are mostly interchangeable. Why would you want to? On a motor bike pedaling is secondary. The shorter pedal arms make it much more convenient for me. However on a sixteen inch bike they usually are not interchangeable so I didn't bother.

I pulled the handlebars and the goose neck from the bike. Those high rise handle bars are good to use if you need to sit low on the bike for balance and your knees hit on a regular handlebar. Mine always hit on a mountain bike it seems. I also pull the front wheel since the spare tire and tube are good to have around. It's easier to pull the whole thing than to remove the tire. I also pull the seat and post. The seat is too small for sure but the mounting hardware under the seat is pretty universal.

At this point I put the frame out for the metal junkers to pickup. If I still drove I might take it to the crusher myself. I expect doing that you can more than repay yourself for the purchase of a donar. For instance the rear wheel is about thirty bucks. The chain is over five... The front wheel is probably the same. You also have the equivalent of one new tire (between the front and rear ones) and a couple of good tubes if you are lucky. The seat hardware and handlebars are worth something down the road. In other words it was a good buy so far.


I shot this before I added the handlebars and goose neck to my stash.

I have two possibilities for the next step. I can weld a scooter sprocket to the bike wheel, or I can weld a bike sprocket to the motor. I have a bike sprocket on the way, and the scooter sprocket is easy enough to come up with. I am going to do the one that is the highest likelihood of success. I wound up doing the scooter sprocket weld to the bike sprocket on the wheel.

I just bid on ebay on a 350 watt currie three hole bolt pattern motor. If you hold on a bit I will know if the mount from a tnc bike motor can be modified. I have the mount on the way it should be here first of the week.

Also today I ordered three on-off-on switches on ebay. I probably won't need them but I wanted them as an idea of the price of the build. I have three e bikes already I plan to just switch the drive I am building for one of those. So I can reuse the switch. This kind of switch is available at the auto parts store. I just wanted to get them on ebay.

About that motor thing, since I have never built with a bike wheel driver I'm not sure but the 350 does a good all around job. Since I run them without being geared down, it's a little hard to guess. That motor will run at 2600 rpms no load. With my fat butt I have no idea what it is. I know I need to pedal some on the hills to keep it from bogging down. I usually set the bike on the third smallest rear gear, then use the front gears to actually set the bike up. Up hills I use the highest gear, starting I try to use the middle or smallest. Then switch it back to high on the first hill. that seems to work best.

I have been thinking about the pusher frame. I have used two types and either works pretty well. I am pretty sure that I will use it on the 24" bike I have a pusher on now. I might buy a different one though. It just depends on what is more convenient at the time. I have five bikes in my shop now. Two have pusher motors and two are just riders. If I had any sense I would just convert one of the old 20" bikes to a pusher. I have used it as a hub motor bike but I didn't like the way it worked. The pusher might be even worse, but then again why not.

Either way I think I will buy a solid L channel that comes in 36" length. I can cut it in half and have two 18" side rails. To figure how long your pusher has to be is pretty simple. The distance from the axle to the rear of the bike wheel is about half the bike height. A twenty six inch should be 13" plus one inch or 14" from the axle hole to the rear of the bike plus the length needed for the pusher wheel. In this case eight inches plus a couple of inches extra at the rear of the pusher. So I figure for a 26" bike I need 14" + 8" + 2" = 24"

I want one piece of metal bolted to the bike on each side. Those two will be part of the bike frame so to speak. I can buy one ten inch L bracket, then use a rotozip to cut it in half. I would end up with two ten inch pieces of heavy metal. One of the other benefits of using the L bracket is that it is predrilled so it is precisely the same on both legs. Also by going that way I can use the bracket on any size bike and just choose different predrilled holes to adjust the pusher to any size bike.

Since I lost the bid on the new motor, I decided that I had enough motor bikes and it was god's way of telling me to work with the bikes I have, So I am going to use the parts from the 450 watt bike I have already. I will most likely use the sprocket that is on that wheel now to build the bicycle wheel pusher as well. The switch will be reusable as well. I want to see if I can make the TNC motor mount work. That is my only question At this point.

Okay review step one was to find a small bike and then to remove the rear wheel.

Step two is to buy a motor.

So most likely you will wind up with a scooter motor. The are almost perfect for building pusher bikes. They come in all kinds of power and mounting configurations. I will show you how to build with a currie motor scooter motor. It looks like this. NEW IZIP 500 24VOLT ELECTRIC SCOOTER MOTOR/ PARTS - eBay (item 320386087798 end time Jun-25-09 15:21:34 PDT)]I build exclusively with motors of this configuration. The come from 200 watts to 1200 watts. I have built with the 250 350 and 450. The more watts the more power. Also the more watts the more expensive. I also always build with 24 volts. I don't like the expense and weight of more batteries but that's just me.

Step three is a decision... the motor and the bike wheel have mismatched sprickets. You can put a bike sprocket on the motor or a scooter sprocket on the wheel. I chose to risk the $5 wheel rather than my $35 motor.

I bought a small scooter sprocket from TNC scooter store. I got a 55 tooth sprocket but you can get others. I welded mine to the sprocket on the bike. If you don't have access to a welder or a friend with one you can always find a shop to do it or you can drill and bole the new sprocket on. If you just use your imagination you will have a rear wheel that looks like this.... this next one is a not so good picture of the rear of the sprocket which is where I welded it. Oh yeah be sure it is centered..

STEP FOUR

You can use a the bike bracket from TNC scooters to mount the motor onto the wheel axle. I had a mount bracket that I was already using on the bike so I kept it. Mounting th motor should not be a problem.

Use your imagination and it shouldn't be much of a job to make a unit with motor and wheel on the axle.

STEP FIVE

To manage step five you have to build a trailer frame. Again welding is better but you certainly can bold this frame together. The pusher wheel is actually a bob tail trailer.



so to build one you need to make two side rails. One end attaches to the bike and one to the axle of your rear wheel. The rails are best left without a connection between them. It is easier to remove the wheel if you can just remove the whole rail. So this is what you need to build.


You need two of those.... You can build exactly like that or better depending on what you have laying around the shop.

FAQ..

How long should it be.... as long as necessary. It needs to be at least (half the size of there rear bike wheel + half the size of the pusher wheel+ two inches) that is bike axle to pusher axle hole. You probably want some excess tail. (No crude remarks please)

What should I use for the sides. I used square tubing for the one you see but I have also used the solid L channel pieces from Home depot.

How do I attach it to the bike. However you can. There are usually some holes around the rear axle of the bike to use for attaching. I usually attach most metal to the bike so that I can work with it separately from the trailer.

What are those L brackets on top of the frame. If you look at the picture of my pusher you will see that I put the batteries right onto the pusher. The L brackets are what I use to hold them.

Now at this point you should have the pusher attached to the bike. Congrats you are almost finished.

step six

the last thing to do is to wire the bike up. I use an on off on switch it give me a two speed helper motor. One that steps right out there.

the diagram is easy to follow you have the negative wire of the motor going to the negative terminal of one battery. The positive wire from the motor goes to the center terminal of the switch.

One wire goes from each of the end terminals on the switch to one of the positive battery terminals. Then the last wire goes from the unused negative battery terminal to the positive terminal on the OTHER battery. If you get it right your switch will provide half power for starting from a stop to full power to running.

Be sure to wire in a fuse. A 40a will not melt the wires and give you some protection... You can try a thirty but it might blow.

Good luck you are ready to roll....

I need to call these things something so I decided to go with PAT ... Pedal Assist Trailer...

Its a trailer with a wheel that has the power. The trailer pushes the bike. The trailer bolts onto the rear of the bike and the motorized third wheel pushes it along. The unit is self contained and pushes the bike along..